Manufacture of tanning substances



Patented Jan. 22, 1935 1,988,985 MANUFACTURE F TANNING SUBSTANCES Josef Solid-fer, Basel, Switzerland, assignor to the firm of I. B. Geigy A. G., Basel, Switzerland No'Drawing. Application August 24, 1934, Se-

rial No. 741,349. In Germany September 18,

v 3 claims. (CL 149-4).

This invention is an improvement in or a modiimproved fastness to light. Obviously in the presfication of that described inU. S. specification No. ent case as well as. in the aforesaid application 1,901,536. r 7 Ser. No. 629,239 there is question of the para-de- That specification describes a manufacture of rivative of dioxy-diphenyl sulphone. tanning agents by heating in an acid solution the d The following example illustrates the invention, 5

sulphonic acid of an aromatic hydrocarbon tothe parts being by weight: gether with formaldehyde and a dioxydiphenyl 180 parts of oleum of 63 per cent strength are sulphone. It is not possible in this process to readded in the cold to 216 parts of crude cresol place the sulphonic acid of the hydrocarbon by D. A. B. W and the mixture is then heated for 10 a sulphonic acid of a phenol, since in this case half an hour at sc -100 c. 150 parts-of crude 10 there would be formed, in the course of the conphenol, consisting of a mixture of ortho-cresol densation, resins which are insoluble in water and and phenol, are then added andthereaction mixare, as such, themselves useless for tanning pur-' ture is heated for one hour at 170 C. whilst air poses. Also it is not possible to combine sulphonic is passed through it. At the end of this operation acids of phenols with the valuable dioxydiphenyl the mixture contains about 1'12 parts of cresol 15.

sulphones to produce tanning substances by sulphonic acid and 280 parts of p-dioxydiphenylmeans of the sequence of I reactions des cribed in sulphone and methyl derivatives thereof. After U. S. application ser, No. 629,239, nled August 1'7, addition of a further 100 parts of cresol sulphonic 1932, that is to say by the action of formaldehyde acid the whole is neutralized, then subjected to on a dioxy-diphenyl sulphone in an alkaline solu- .steam distillation to remove excess of phenols, tion and subsequent condensation with an arorendered alkaline tophenolphthalein by means of matic sulphonic acid under acid conditions. caustic alkali solution and then heated to boiling According tothis invention, by heating adioxywith the addition of 150 parts of formaldehyde diphenyl sulphone together with formaldehyde solution of per cent strength. After heating a 25 and a sulphonic acid of a phenol in an alkaline has been continued for about 6-8 hours the reacsolution valuable tanning substances are obtained tion mixture is rendered faintly acid, whereby without the separation of deleterious resins, there is obtained a solution ready for use for tanwherea's, as is known, the condensation of dioxyning and having the same properties diphenyl sulphones with formaldehyde alone as the products described inthe parent specinca o under alkaline conditions leads to resins which tion. By conducting the condensation under are insoluble in water (compare German specipressure the duration 'of the heating operation can fication No. 464,088). r be reduced.

The possibility of combining the components WhatIclaim is:- Y directly in an alkaline medium could not be ex- 1. A process for the manufacture of tanning pected in view of previous knowledze. Furthersubstances, consisting inheating adioxy-diphenyl more it is no longer necessary, as it is in the .procsulphone with formaldehyde and a sulphonic acid ess of the U. S. specification No. 901,536, to preof a phenol in an alkaline solution.

' in a separate 2. A' process for the manufacture of tanning pare the dioxy-diphenyl sulphone I operation, but this can be prepared and further substances, consisting inheating adioxy-diphenyl condensed in one operation; this possibility rensulphone with formaldehyde and a sulphonic acid 40 ders the process simpler and more economical. of cresol in an alkaline solution.

Leather prepared with the aid of the tanning 3. A tanning substance consisting of the prodsubstances of the present invention resembles, in not of reaction of a dioxy-diphenyl sulphone with agents described in the U. S. specification No. in an alkaline solution.

. JosEr' scnAr'ER.

ct of its fullness, that prepared with the formaldehyde and a sulphonic acid of a phenol 

